Update PHP's Get Giphy GIF example to v2 images

[thinkverse]

This PR updates the PHP Get Giphy GIF example to use the latest v2-8.1 docker image and fixes an issue where the search query wasn't URL encoded causing the API request to fail sometimes.

Screenshot of working v2 image

[Meldiron]

Thank you so much for the PR 🤩. We're adding the hacktoberfest-accepted label to ensure this PR counts towards your Hacktoberfest contributions count. With that said, please stay active on this PR to address any comments once you receive a review. Happy Hacktoberfest! 🎃

[stnguyen90]

@christyjacob4 or @TorstenDittmann, would you please merge this when you get a chance?

[christyjacob4]

THANK YOU! All changes merged 🥳

Please reach out to me on our Discord server if you would like to claim your Appwrite swags! As a way of saying thank you, we would also love to invite you to join the Appwrite organization on GitHub. Please share your GitHub username with us on Discord.  

You can accept the invite by visiting https://github.com/orgs/appwrite/invitation. By joining our team, you will officially be an Appwrite maintainer on GitHub.

You can change your membership visibility settings, so your new Appwrite team membership badge will show up on your personal GitHub profile.

Please feel free to look for more PRs you might be interested in helping with on our long list of Hacktoberfest friendly issues and help make Appwrite better :)